206 



and Prof Huxley ^ ) ; the last mentioned naturalist says „a fibrous 

 expansion extends from the vertebral column over the anterior face 

 of the stomach, the liver, the dorsal and front aspect of the peri- 

 cardium, to the sternum and the parietes of the thorax, separating 

 the thoraco-abdominal space into a respiratory and a cardio-abdomi- 

 nal cavity, and representing the oblique septum of the bird." I would 

 myself venture to suggest that this structure, which is very 

 plainly visible in the dissection of a Crocodile, is the equivalent 

 not only of the oblique septum in the bird but also of 

 the socalled „omentum". I believe also that it is the 

 specialized and rather more highly developed repre- 

 sentative of the fold of peritoneum described above 

 in Monitor. 



There is therefore in Monitor a commencement of 

 that subdivision of the coelom, which reaches its ex- 

 treme in the higher Sauropsida. 



Granting that there is a special relationship between the M o n i - 

 tores and the Cr o cod ilia, it is probable that the latter have been 

 derived from some form ressembling the former and not vice versa. 

 There is no difficulty in the assumption that the primitive Sauropsida 

 were more Lacertilian than Crocodilian in their characters ; if however 

 the comparisons put forward in the present paper be right, it is ne- 

 cessary to argue the high antiquity of a Lacertilian closely allied to 

 the existing Monitors. This may conceivably be Protorosaurus. 



In any case the facts brought forward in the present paper seem 

 sufficient to remove the Monitores from the Lacertilia vera. 



London, Febr. 14. 



Zur Frage über die Beziehungen zwischen der Zahl der Fasern 



in den Neryenstämmen und dem Körpergewicht 



hei Säugetieren. 



Vorläufige Mitteilung von Ph. Waszkiewicz. 



Die genauere Kenntnis der Faserzahl in den entsprechenden Ner- 

 venstämmen bei Tieren von verschiedenem Körpergewicht verspricht 

 manche wertvolle Einblicke in den Aufbau des tierischen Organismus 



1) Proc. Zool. Soc. 1882, p, 568. 



